Measuring cap for a container that can house a pressurized fluid, and container provided with one such cap

ABSTRACT

The invention relates to a measuring cap ( 1 ) for a pressurised container ( 2 ), comprising: a body ( 8 ) having an axial fluid channel ( 12 ), shaped in order to be inserted into the container ( 2 ) through the neck ( 5 ); a sealing joint ( 15 ) shaped bear on a portion of the body ( 8 ); an assembly ring ( 16 ) which is used for removably securing the measuring cap ( 1 ) to the container ( 2 ) and which is removable; and a closure member ( 17 ) for selectively closing and opening the fluid outlet channel ( 12 ).

TECHNICAL FIELD OF THE INVENTION

The present invention concerns pressurised receptacles able to contain a fluid, and more particularly the means of closing such pressurised receptacles.

Known pressurised receptacles are of the aerosol type.

An aerosol is a set of solid or liquid particles of a chemical substance given in suspension in a gaseous medium.

In normal life, the term “aerosol” also designates the receptacle containing a mixture of a product and a propellant gas. The propellant gas creates a pressure inside the receptacle. By opening an outlet valve, the mixture is expelled outside the pressurised receptacle. The product is atomised in the form of an aerosol, that is to say in fine particles in suspension in air.

The propellant gas is normally nitrogen since it is an inert gas and therefore less dangerous than propane, butane and other flammable hydrocarbons, which do not however have an effect on the ozone layer.

A known aerosol receptacle comprises a bottom, a lateral wall and a neck, and is usually produced from aluminium. The thickness of the receptacle is designed to withstand up to 18 bar pressure inside. There exist such aerosol receptacles having various capacities.

Such receptacles are described in particular in the documents U.S. Pat. No. 3,977,576, FR 2909981 A1, U.S. Pat. No. 6,253,970 B1 and U.S. Pat. No. 3,187,962.

These known receptacles are closed by a dispensing valve designed to be non-removable. The receptacles cannot therefore be reused. When a pressure is applied to an operating member connected to the dispensing valve, the seal is broken, enabling the product contained in the receptacle to pass into the valve and to escape to the outside of the receptacle.

Aerosols, that is to say the pressurised receptacles provided with a non-removable dispensing valve, are governed by very strict and draconian safety standards. In all known aerosols, the dispensing valves are not removable and they do not make it possible to effectively measure out the flow of product emerging from the pressurised receptacle. The internal pressure allowed by the standards is limited to 12 bar at 50° C. In addition, the filling of known aerosols is limited by strict standards to 66% of the volume, which is itself a maximum of one litre.

Known aerosols function only when they contain a non-granular fluid, otherwise the dispensing valve becomes blocked and the aerosols can no longer dispense fluid.

DISCLOSURE OF THE INVENTION

A first problem proposed by the present invention is to design a closure means for a pressurised receptacle able to contain a fluid that is removable and makes it possible to measure out the emerging product, and the safety in use of which is ensured up to pressures of more than 20 bar.

A second problem that is at the basis of the present invention is to design a pressurised receptacle that allows an intermittent thrust and can contain and dispense even a granular fluid.

Because aerosols do not function with a granular fluid, aerosol valves do not make it possible to solve these problems.

The idea that is at the basis of the invention is to design a reliable removable measuring cap and to use it in association with a receptacle containing a fluid at a pressure appreciably greater than the pressures normally allowed for aerosols, for example around 30 bar.

To achieve these aims as well as others, the invention proposes, according to a first aspect, a measuring cap for a pressurised receptacle able to contain a fluid, the receptacle comprising a bottom and a substantially cylindrical lateral wall that narrows towards a neck having a front neck face and an internal neck edge, comprising:

-   -   a body with a longitudinal axis having:         -   a penetrating part, which is conformed so as to enter the             neck of the receptacle and comprises a radial peripheral             protrusion able to engage in abutment against the internal             edge of the neck,         -   an emerging part, with an axial fluid passage communicating             with the inside of the receptacle and communicating with the             outside of the receptacle through a fluid outlet passage,         -   a sealing shoulder at the junction between the penetrating             part and the emerging part,     -   a sealing joint, conformed so as to bear on the sealing shoulder         and on the front neck face,     -   an assembly ring able to be fixed removably to the emerging part         of the body while axially clamping the first sealing joint         against the front neck face and against the sealing shoulder,         and     -   a closure member able to selectively close and open the fluid         outlet passage, controlled by an operating member accessible on         the emerging part of the body.

Such a measuring cap is removable. Thus the receptacle that it closes can easily be reused, which reduces the quantity of waste produced. Such a measuring cap is therefore ecological. Such a measuring cap does not comprise a valve. And the pressurised receptacle provided with such a removable measuring cap is not constrained by the strict aerosol standards, nor by other rules if the volume of the receptacle is less than one litre and the pressure produced per volume is less than 50 bar/litre.

This measuring cap is simple in design; it comprises only three main elements that can be preassembled, and a fourth element to be assembled in order to connect the measuring cap to the pressurised receptacle. It is therefore also simple to use.

Such a measuring cap is compatible with conventional receptacle bodies for aerosols so that it is possible to profit from the low cost of these mass-produced receptacles.

In addition, the cap according to the invention is a measuring cap and the user can therefore choose the rate of flow of product out of the pressurised receptacle.

Advantageously, it is possible to provide for the radial peripheral protrusion to comprise a frustoconical portion, the cone angle of which corresponds substantially to the inclination of the internal neck edge of the receptacle.

The mechanical thrust forces on the neck of the receptacle are thus best distributed.

Advantageously, provision can be made for the penetrating part to comprise at least one recessed lateral face defining a width less than the diameter of the neck of the receptacle.

The introduction of the body into the pressurised receptacle is thus facilitated.

Provision can advantageously be made for said at least one lateral face to be positioned so that it allows a slight local deformation of the neck that generates a leakage beyond a predetermined pressure inside the receptacle.

This is an inexpensive safety element that is easy to implement.

Provision can advantageously be made for the measuring cap to be produced from metal or plastics material.

The use of plastics material reduces the manufacturing costs of the measuring cap since plastics material is less expensive than metal. However, metal will have better mechanical strength.

In the case of a metal measuring cap, provision can advantageously be made for the metal to be stainless steel or an aluminium alloy.

These metals are widespread and forming thereof by numeric control or any other means is well known.

Advantageously, provision can be made for the assembly ring to be fixed to the body by screwing, pressing or cottering.

These types of assembly make it possible to obtain a measuring cap that is removable.

Advantageously, provision can be made for the penetrating part of the body to comprise two lateral flats on either side of the longitudinal axis of the body. One of these two flats producing the lateral face.

Provision can advantageously be made for the assembly ring to comprise a peripheral skirt surrounding the neck of the receptacle, leaving a leakage space between its end edge and the peripheral wall of the receptacle.

This is an inexpensive safety element that is easy to implement, which guides away from the user the jet of fluid emerging from the receptacle through the sealing joint in the event of overpressure.

By surrounding the neck of the receptacle, the assembly ring also fulfils the function of reinforcement of the neck, opposing the action of the internal pressure of the receptacle, which tends to enlarge the neck.

Advantageously, provision can be made, according to a first embodiment, for the closure member to be a rod slidably mounted in the axial fluid passage between a closure position and an open position, and comprises two annular grooves able to receive annular closure joints.

The travel of the closure element is limited between two predefined positions. This prevents any risk of the closure element leaving the axial fluid passage unexpectedly.

According to a second embodiment, provision can advantageously be made for the closure member to be a locking screw that is actuated by screwing or unscrewing in the body.

The penetration of the locking screw in the body is chosen precisely by a user by screwing this locking screw to a greater or lesser extent. And the structure is well suited to applications in which the fluid contains powders or solid suspensions.

Provision can advantageously be made for the closure member also to comprise a closure element positioned in the axial fluid passage close to the neck of the receptacle and held distant from the latter by a spring or by the internal pressure of the receptacle.

The closure element fulfils a dual function, namely the valve function during filling and the safety element function.

According to a second aspect, the invention provides a receptacle able to contain a pressurised fluid, closed by a measuring cap according to first aspect of the invention, and having an initial internal pressure greater than 20 bar.

Such a receptacle does not need to comply with aerosol standards since it does not comprise a fixed valve and the cap is removable.

SUMMARY DESCRIPTION OF THE DRAWINGS

Other objects, features and advantages of the present invention will emerge from the following description of particular embodiments, given in relation to the accompanying drawings, among which:

FIG. 1 is a view in longitudinal section of a pressurised receptacle provided with a measuring cap according to a first embodiment of the invention;

FIG. 2 is an exploded view of the elements to be assembled for producing the measuring cap of FIG. 1;

FIG. 3 is a side view of the body of the measuring cap of FIG. 1 in a state in which it has entered the neck of the receptacle;

FIG. 4 is an enlarged view in longitudinal section of the measuring cap of FIG. 1;

FIG. 5 is a view in longitudinal section of the measuring cap of FIG. 1 in a closed position;

FIG. 6 is a view in longitudinal section of an enlargement at the annular groove of the measuring cap of FIG. 1 in an intermediate position;

FIG. 7 is a view in longitudinal section of the cap of FIG. 1 in an open position;

FIGS. 8 and 9 are views in longitudinal section of a pressurised receptacle provided with a measuring cap according to a second embodiment;

FIGS. 10 and 11 are views in longitudinal section of a pressurised receptacle provided with a measuring cap according to a third embodiment.

DESCRIPTION OF PREFERRED EMBODIMENTS

FIGS. 1 to 7 illustrate a first embodiment of the invention, in which a measuring cap 1 is connected by screwing to a pressurised receptacle 2. The numerical references therefore refer to the same elements in all these figures.

FIG. 1 illustrates the receptacle 2 closed by the measuring cap 1.

The receptacle 2 comprises a bottom 3 and a cylindrical lateral wall 4 that narrows towards a neck 5. The narrowing is provided at an angle of inclination p. The neck 5 is produced by an outward folding on itself of the material constituting the receptacle 2. The neck 5 comprises a front neck face 6 and a bottom neck edge 7. The receptacle 2 is designed to contain a pressurised fluid.

To describe the measuring cap 1, FIG. 4 is considered, which illustrates more precisely in section the elements making up the measuring cap 1.

The measuring cap 1 comprises a body 8 with a longitudinal axis I-I, a sealing joint 15, an assembly ring 16, a closure member 17 and an operating member 18.

The body 8 comprises a penetrating part 9 and an emerging part 11, which join at a sealing shoulder 14 oriented towards the emerging part 11.

The penetrating part 9 comprises a substantially cylindrical distal part and a radial peripheral proximal protrusion 10. The radial peripheral protrusion 10 comprises a frustoconical portion 10 a (FIG. 2) with a cone angle α.

The cone angle α is designed to correspond to the angle of inclination β so as to distribute the mechanical forces of the measuring cap 1 on the receptacle 2.

The penetrating part 9 comprises two lateral flats 19 a and 19 b (FIGS. 2 and 3) on either side of the longitudinal axis I-I of the body 8. These two lateral flats 19 a and 19 b (FIGS. 2 and 3), parallel to the longitudinal axis I-I, are designed to enable the penetrating part 9 of the body 8 to be introduced into the receptacle 2 through the neck 5.

To do this, the width 190 of the penetrating part 9, at the two lateral flats 19 a and 19 b, is designed to be less than the diameter D of the neck 5 of the receptacle 2.

As an alternative, the penetrating part 9 of the body 8 can comprise non-parallel, non-symmetrical lateral faces, or a single lateral face. The main thing is to enable the penetrating part 9 to enter the neck 5 and to afford a sufficient surface for the sealing joint 15.

The emerging part 11 comprises a through axial fluid passage 12, a fluid outlet passage 13 and a threaded portion 11 a on its external surface close to the sealing shoulder 14. The fluid outlet passage 13 and the axial fluid passage 12 communicate with each other in order, once the measuring cap 1 is connected to the receptacle 2, to enable the product contained in the receptacle 2 to flow.

The axial fluid passage 12 comprises an intermediate shoulder 30 disposed in an intermediate position between the fluid outlet passage 13 and the upstream orifice 12 a of the axial fluid passage 12 and having its face oriented in the upstream direction.

The sealing joint 15 is annular and is conformed so as to bear on the sealing shoulder 14 and on the front neck face 6.

The assembly ring 16 comprises a substantially cylindrical portion 25 having a threaded through opening 24 and a peripheral skirt 20. The thread of the threaded through opening 24 of the assembly ring 16 is designed to correspond to the thread of the threaded portion 11 a of the emerging part 11.

The closure member 17 is able to selectively close and open the fluid outlet passage 13. It is controlled by an operating member 18 accessible on the emerging part 11 of the body 8.

The closure member 17 is a rod comprising two annular grooves 22 a and 22 b with a frustoconical profile and offset longitudinally from each other at a separation greater than the axial separation between the fluid outlet passage 13 and the intermediate shoulder 30 (FIG. 4).

Each annular groove 22 a and 22 b is provided with a closure joint, respectively 23 a and 23 b. Each closure joint 23 a and 23 b can advantageously be made from elastomer and be cylindrical and tubular in shape with a circular cross section of constant thickness. The upstream annular groove 22 a has a depth that decreases in the direction of the upstream orifice 12 a.

The closure member 17 comprises an intermediate portion 170 situated between the two annular grooves 22 a and 22 b and is cylindrical in the embodiment in FIGS. 1 to 7. This intermediate portion 170 could however be frustoconical, or more widely any shape to be determined according to the granulometry of the fluid to be dispensed.

FIGS. 5 to 7 illustrate the sliding of the closure member 17 in the axial fluid passage 12.

FIG. 5 illustrates the measuring cap 1 in a closure position P1 in which the product contained in the receptacle 2 cannot be expelled to the outside of the receptacle 2: the upstream closure gasket 23 a is engaged in a cylindrical portion with a small diameter of the axial fluid passage 12, between the fluid outlet passage 13 and the intermediate shoulder 30, and then provides sealed closure of the axial fluid passage 12.

FIG. 6 illustrates the closure member 17 to a larger scale in an intermediate position P. In this intermediate position P, the upstream closure joint 23 a is in line with the intermediate shoulder 30 and produces a partial opening allowing the pressurised fluid to pass at a rate that the user can control by axial movement of the closure member 17. The frustoconical form of the annular groove 22 a gradually forces the upstream closure joint 23 a, which allows gradual opening.

FIG. 7 illustrates the measuring cap 1 in an open position P2, in which the product contained in the receptacle 2 is expelled to the outside of the receptacle 2.

As illustrated in FIG. 5, when the closure member 17 is in the closure position P1, the fluid cannot be expelled since the axial fluid passage 12 is closed off by the closure member 17. Through the pressure inside the receptacle 2, the closure member 17 is pushed outwards, and its travel is limited by a shoulder 26 provided on the closure member 17 and which bears axially against the intermediate shoulder 30 of the axial fluid passage 12, preventing the closure member 17 escaping.

The sealing is provided in the closure position P1 by the upstream closure joint 23 a, which is pressed in a cone against the wall of the axial fluid passage 12.

In the event of overpressure inside the receptacle 2 beyond a given pressure value, leakage is possible through the sealing joint 15 and in the space E between the peripheral skirt 20 and the receptacle 2.

When a user applies a force F (FIG. 7) on the operating member 18, the rod of the closure member 17 slides in the axial fluid passage 12. The fluid does not escape, because of the upstream closure gasket 23 a, which is always pressed against the wall of the axial fluid passage 12. As will be understood from FIG. 6, the closure is provided effectively and very economically with a cylindrical closure joint 23 a engaged in a frustoconical annular groove 22 a.

FIG. 7 illustrates the elements in the open position P2 in which the fluid is expelled. The closure member 17 is lowered sufficiently to break the seal at the upstream closure gasket 23 a.

The fluid is therefore expelled in a controlled fashion towards the outside, passing through the axial fluid passage 12 and then the outlet passage 13. The second closure gasket 23 b provides the seal for preventing a quantity of fluid being able to be extracted towards the operating member 18.

The operating member 18 is a hood provided with a threaded bore 18 a for fixing thereof by screwing on the threaded distal end 17 a of the closure member 17. As an alternative, the operating member 18 can be fixed by clipping, crimping, pooping or adhesive bonding.

In the embodiment described, an elastic means 17 b of the helical compression spring type is engaged between the operating member 18 and the body 8 in order to assist closure if the pressure is too low inside the receptacle 2, or if the fluid is sticky.

The elastic means 17 b is however not essential and it can be considered that the pressure inside the receptacle 2 is sufficient to enable the closure member to slide as far as the closure position P1 with suitable fluids to be dispensed.

If necessary, the fluid contained in the receptacle must be previously filtered.

FIG. 2 explains the order of assembly of these elements in order to produce the measuring cap 1.

The sealing joint 15 is arranged on the inside of the assembly ring 16 so that, once the whole is assembled, the sealing joint 15 makes the seal at the neck 5 of the receptacle 2. The closure member 17 without the operating member 18 is slidably mounted in the axial fluid passage 12, engaging it through the upstream orifice 12 a. The closure gaskets 23 a and 23 b will have been previously mounted in the respective annular grooves 22 a and 22 b provided in the closure member 17. The assembly ring 16 provided with the gasket 15 is engaged on the body 8. The operating member 18 is screwed on the distal end 17 a of the closure member 17, locking the closure member with respect to rotation by engagement of a screwdriver in a slot 17 c provided at the proximal end of the closure member 17. As an alternative to the slot 17 c, any other locking means can be provided, and the slot 17 c can have any other profile.

Next the penetrating part 9 can be introduced obliquely in the neck 5 of the receptacle 2. This introduction is made possible in particular through the presence of the two lateral flats 19 a and 19 b. Then the measuring cap 1 is positioned so that the radial peripheral protrusion 10 engages in abutment against the internal edge of the neck 7.

Then the assembly ring 16 is screwed on the threaded part of the emerging part 11 of the body 8. The assembly ring 16 axially clamps the first gasket 15 against the front neck face 6 and against the sealing shoulder 14. The connection of the measuring cap 1 with the receptacle 2 is effected.

The peripheral skirt 20 surrounds the neck 5 of the receptacle 2, leaving a leakage space E between its extreme edge 21 and the peripheral wall 4 of the receptacle 2.

The invention also ensures the safety of the users, through a safety leak when a predetermined maximum pressure is reached inside the receptacle 2. To do this, the lateral flats 19 a and 19 b are positioned recessed so that they allow a slight local deformation of the neck 5, producing an area of less strength. Thus, when the predetermined maximum pressure is reached, the neck 5 is deformed outwards and the gasket 15 is less crushed, which gives rise to a safety leakage.

This first embodiment is particular suitable for fluids with a granulometry of less than 500 μm.

FIGS. 8 and 9 illustrate a second embodiment of the present invention, in which the receptacle 2 (FIG. 1) is closed by the measuring cap 100. As in the first embodiment, the measuring cap 100 is connected to the receptacle 2 by screwing.

The same essential means are marked by the same numerical references as in FIGS. 1 to 7.

The measuring cap 100 comprises a body 80 with a longitudinal axis II-II, a sealing joint 15, an assembly ring 16 and a closure element 40.

The main difference between the first and second embodiments lies in the fact that, in the second embodiment, the closure member 41 and the operating member 42 are in a single piece and produce the closure element 40. As an alternative, the operating member 42 can be a part attached by adhesive bonding, clipping, hooping or screwing.

The axial fluid passage 12 comprises a threaded top portion 12 b, a bottom shoulder 43 and an intermediate shoulder 44 a. The bottom shoulder 43 is placed in an intermediate position between the fluid outlet passage 13 and the upstream orifice 12 a of the axial fluid passage 12.

The closure element 40 is able to selectively close and open the fluid outlet passage 13. It is controlled directly by an action of a user on the operating member 42 accessible on the emerging part 11 of the body 80.

The closure member 41 is a rod comprising four sections. A first top section 41 a is partially threaded in its part close to the operating member 42. Its second portion 41 b has a reduced diameter and comprises an annular groove 45 with a frustoconical double profile.

The annular groove 45 may however have any other form producing a bulge, for example a spherical profile.

The first portion 41 a and the second portion 41 b are joined by a shoulder 44 a. The third portion 41 c has a frustoconical profile and joins the fourth portion 41 d at a point that terminates the rod.

The annular groove 45 is provided with a closure joint 46. As in the previous embodiment, the closure joint 46 can advantageously be made from elastomer and be tubular and cylindrical in shape with a circular cross section with constant thickness. The annular groove 45 has a depth that increases in the direction of the upstream orifice 12 a.

In this embodiment, the measuring cap 100 also comprises a closure element such as a ball 47, engaged in axial movement in the axial fluid passage 12, and held in position by a conical spring 48. The diameter of the ball 47 is chosen so as to be sufficient in order not to enter the receptacle 2, and sufficient to create a seal when the ball 47 is in contact with the bottom shoulder 43.

In an embodiment that is not illustrated, the spring could be straight and in abutment on the plunger tube 49 (FIGS. 8 to 11), the inside diameter of which is less than that of the ball 47.

The functioning of the measuring cap 100 will now be described.

In the position illustrated in FIG. 9, the measuring cap 100 is in a closure position in which the product contained in the receptacle 2 cannot be expelled to the outside of the receptacle 2. The point-shaped fourth portion 41 d of the closure member 41 cooperates with a narrowing 50 of the axial fluid passage 12, upstream from the fluid outlet passage 13. The narrowing 50 forms a seat against which the fourth portion 41 d can come to bear, then providing a sealed closure of the axial fluid passage 12.

When the closure member 41 is in an intermediate position, the point-shaped fourth portion 41 d no longer cooperates with the narrowing 50 of the axial fluid passage 12. In this way a partial opening is produced, which allows the pressurised fluid to pass at a rate that the user can control by axial movement of the closure member 41 by screwing the closure element 40 to a greater or lesser extent. The point-shaped form of the fourth portion 41 d allows gradual opening.

In order to adapt the flow rate of the fluid according to the granulometry of the fluid to be dispensed, the diameter of the third portion 41 c and the shape of the point 41 d can be modified.

In an open position, the product contained in the receptacle 2 is expelled to the outside of the receptacle 2 since the third portion 41 c is no longer in contact with the narrowing 50 of the axial fluid passage 12, which has the effect of breaking the seal.

When a user unscrews the closure element 40, the rod of the closure member 41 rises in the axial fluid passage 12. The closure seal 46, which remains pressed against the wall of the axial fluid passage 12, prevents the progress of the fluid towards the operating member 42.

The ball 47 fulfils the dual function of filling valve and safety valve. The function of the safety valve is illustrated in FIG. 8.

For filling, the closure element 40 is absent, the fluid outlet passage 13 is blocked, and the ball 47 is pushed by the conical spring 48 towards the bottom shoulder 43. By contact between the ball 47 and the bottom shoulder 43, the seal is provided.

During filling, the fluid entering under pressure pushes the ball 47 towards the inside of the receptacle 2 so that the ball 47 is no longer in contact with the bottom shoulder 43 and allows the pressurised fluid to pass towards the inside of the receptacle 2.

The ball 47 fulfils the role of non-return valve in that it prevents the fluid contained in the receptacle 2 from emerging since the fluid that moves towards the outlet pushes the ball 47 in contact with the bottom shoulder 43, creating the seal and preventing the expulsion of pressurised fluid towards the outside of the receptacle 2.

The ball 47 also fulfils the role of safety valve since, if the closure 40 element is unscrewed by accident, the ball 47 rises and comes into contact with the bottom shoulder 43 in order to create the seal. The pressurised fluid is then not expelled to the outside of the receptacle 2.

FIGS. 10 and 11 illustrate a third embodiment of the invention. The difference compared with the second embodiment is the absence of a conical spring. The ball 47 is held in position by sufficient pressure inside the receptacle 2 (FIG. 10).

FIGS. 8 to 11 illustrate a plunger tube 49 for guiding the fluid from the inside of the receptacle 2 to the outside.

The ball 47 has a diameter greater than the inside diameter after fitting of the plunger tube 49, so that the ball 47 does not fall into the receptacle 2 (FIG. 11). In this way, the ball 47 is engaged between the plunger tube 49 and the bottom shoulder 43.

The plunger tube 49 is not shown in FIGS. 1 to 7 but can be designed to fulfil in particular the same function of limitation of the travel of the ball 47, or the function of support of the spring 48.

In the embodiments in FIGS. 8 to 11, provision can advantageously be made for the cone of the needle 41 d to have an angle of approximately 60°, and the needle is truncated so as to not to damage the ball 47 when the needle 41 d is in contact with ball 47.

The second and third embodiments are suitable particularly for fluids with a granulometry of less than 2 mm.

The measuring cap can be produced from any material having food characteristics when the receptacle must contain and dispense a fluid for food use. It can be produced from plastics material or metal (for example stainless steel or an aluminium alloy).

The fluid outlet 13 could have any form enabling an extension tube to be fitted for dispensing the fluid more ergonomically.

In an embodiment that is not illustrated, the cone angle α of the frustoconical portion of the radial peripheral protrusion 10 does not correspond to the inclination β of the internal edge of the neck of the receptacle. Thus when the penetrating part 9 is rotated an undercut is created and locks the body 8 firmly.

In another embodiment that is not illustrated based on the embodiments in FIGS. 8 to 11, the ball 47 could be replaced by a cylinder with a diameter substantially less than the diameter of the axial fluid passage 12 and substantially greater than the inside diameter of the spring 48, where applicable. Said cylinder can be provided with a substantially frustoconical groove, like the groove 22 a (FIG. 6). A closure joint, like the closure joint 23 a, is provided in the groove. The seal is achieved as illustrated in FIG. 6, the sealing joint coming into contact with a narrowing of the axial fluid passage, such as the narrowing 50 (FIGS. 8 to 11).

The present invention is not limited to the embodiments that have been explicitly described but includes the various variants and generalisations contained in the field of the following claims. 

1. Measuring cap for a pressurised receptacle able to contain a fluid, the receptacle comprising a bottom and a substantially cylindrical lateral wall that narrows towards a neck having a front neck face and an internal neck edge, characterised in that it comprises: a body with a longitudinal axis having: a penetrating part, which is conformed so as to enter the neck of the receptacle and comprises a radial peripheral protrusion able to engage in abutment against the internal edge of the neck, an emerging part, with an axial fluid passage communicating with the inside of the receptacle and communicating with the outside of the receptacle through a fluid outlet passage, a sealing shoulder at the junction between the penetrating part and the emerging part, a sealing joint, conformed so as to bear on the sealing shoulder and on the front neck face, an assembly ring able to be fixed removably to the emerging part of the body while axially clamping the first sealing joint against the front neck face and against the sealing shoulder, and a closure member able to selectively close and open the fluid outlet passage, controlled by an operating member accessible on the emerging part of the body.
 2. Measuring cap according to claim 1, wherein the radial peripheral protrusion has a frustoconical portion the cone angle α of which corresponds substantially to the inclination of the internal edge of the neck of the receptacle.
 3. Measuring cap according to claim 1, wherein the penetrating part comprises at least one recessed lateral face defining a width less that the diameter (D) of the neck of the receptacle.
 4. Measuring cap according to claim 3, wherein said at least one lateral face is positioned so that it allows a slight local deformation of the neck that generates a leakage beyond a predetermined pressure inside the receptacle.
 5. Measuring cap according to claim 1, wherein it is produced from metal or plastics material.
 6. Measuring cap according to claim 5, wherein the metal is stainless steel or an aluminium alloy.
 7. Measuring cap according to claim 1, wherein the assembly ring is fixed to the body by screwing, pressing or coffering.
 8. Measuring cap according to claim 1, wherein the assembly ring has a peripheral skirt surrounding the neck of the receptacle, leaving a leakage space (E) between its end edge and the lateral wall of the receptacle.
 9. Measuring cap according to claim 1, wherein the closure member is a rod mounted so as to slide in the axial fluid passage between a closure position (P1) and an open position (P2), and comprises two annular grooves receiving annular closure joints.
 10. Measuring cap according to claim 1, wherein the closure member is a locking screw that can be actuated by screwing or unscrewing in the body.
 11. Measuring cap according to claim 10, wherein the closure member also comprises a closure element positioned in the axial fluid passage close to the neck of the receptacle and held distant from the latter by a spring or by the internal pressure of the receptacle.
 12. Receptacle able to contain a pressurised fluid, wherein it is closed by a measuring cap according to claim 1, wherein its initial internal pressure is greater than 20 bar. 